In general, in the field of display, Integrated Circuits (ICs for short), Flexible Printed Circuits (FPCs for short) and Chip On Flexes (COFs for short) are widely used to connect a display apparatus and a driving circuit. A FPC is a highly reliable and flexible printed circuit board which uses a polyimide or polyester film as a substrate, and has characteristics such as high wiring density, light weight, thin thickness, and good bending. A COF is a granular flexible film packaging technology of fixing an IC onto a FPC, and is a technology of combing a chip with a flexible substrate circuit using an additional flexible circuit board as an encapsulation chip carrier.
When the IC, the FPC and the COF are connected to the display apparatus as described above, the connection is realized through bonding by using a bonding process. The bonding process specifically comprises the following steps.
In a first step, an Anisotropic Conductive adhesive (ACF for short) is coated on a display substrate; in a second step, the FPC/COF is aligned to be placed at a specific location; and in a third step, the FPC/COF is pressed fit using a bonding device to be bonded onto the display substrate.
However, in the above bonding process, an intensity of a bonding pressure for the IC, the FPC, and the COF is 1 MPa to 150 MPa per bump (wherein the bump corresponds to an electrode on the display substrate). Due to various factors such as unstable process etc., poor bonding often occurs, which causes the IC, the FPC and the COF etc. to be separated from the display pate later or a degree of adhesion between the IC, the FPC and the COF and the display substrate is not sufficient, thereby resulting in unstable signal transmission.
Therefore, there is a need to detect a display apparatus after the completion of the bonding. In a conventional detection method, after the bonding is completed, a part or even all of the products are randomly selected to be amplified and detected under a microscope, and parameters such as a number, diameters etc. of gold balls at specific observation locations are determined experimentally to determine the yield of the bonding process. The process is complex, and even a detection missing phenomenon easily occurs, resulting in poor characteristics of the products and affecting the performance of the products.